The wave pattern for electrons passing through a double slit, one-at-a-time. If you measure “which slit” the electron goes through, you destroy the quantum interference pattern shown here.

The importance of including exotic “non-classical paths” in analyses of quantum interference has been demonstrated experimentally by physicists in India. Urbasi Sinha and her colleagues at the Raman ...

However, a new study attempts to fill this gap. It suggests that classical interference patterns arise from specific quantum states of light, called bright and dark states.